I believe this is the first Mutual Fund available for the 3d printing market that I can find.

TDPIX just google it and pick Bloomberg for more info. It is $2500 to get in and shares are averaging $10. I got in by ordering it directly on there web site. http://www.3dpfund.com It just came out Jan 30th 2014 so you are getting in at the bottom end. Their Holdings are now posted on the web site..... Good Luck and always do your due diligence.